Microelectronic devices are used in a wide array of products. These devices, including but not limited to memory and microprocessor chips, have been used as components of computers, telephones, sound equipment, and other electronic consumer products. Over the years, manufacturers have improved such microelectronic devices. For example, manufacturers have invented new microprocessor chips with faster processing speeds, and with other improved characteristics, all at a lower cost and price to the end user. These lower prices have made possible the use of such microelectronic devices in products in which they had not previously been used, or in which they had been only sparingly used, such as appliances, motor vehicles, and even lower priced goods, such as toys and games. The increased use of microelectronic devices in such products has enabled their manufacturers to lower the products' cost, provide the products with new features, and increased the products' reliability. The increased speed, versatility, and cost-effectiveness of these microelectronic devices have even facilitated the creation of entirely new types of products.
A major factor in the development of these improved microelectronic devices has been the machines and methods used in their manufacture. The manufacture of microelectronic devices requires a high degree of precision, extremely pure raw materials, and an extremely clean manufacturing environment. If even tiny particles of dust, dirt, metals, and manufacturing chemicals remain upon the surface of these devices, at any stage of the manufacturing process, defects in or failure of the devices can result. For these reasons, makers of these devices have relied increasingly upon specialized machines, manufacturing facilities (also known as “fabs”), and manufacturing methods. These machines and facilities are costly to design, build, equip, and maintain. As a result, it is essential that the machines be reliable, so as to minimize downtime for repair, service, or replacement.
Modern wafer processing machines typically have multiple processing units or chambers. For example, a typical wafer processing machine may have as many as fourteen process chambers. Each of these units or chambers may be independently programmed to accomplish a particular step in the multi-step manufacturing process for microelectronic devices. In the event that even one of the process chambers malfunctions and must be serviced, and if the operator wishes to immediately repair or replace that process chamber, then the entire wafer processing machine must be removed from service for whatever time is necessary to repair or replace that chamber. In some instances, after such repair or replacement, it is also necessary to recalibrate robots, which insert and remove wafers from the replaced process chamber. This recalibration step adds still further downtime to that ordinarily resulting from the repair or replacement of the single process chamber.
This downtime can result in the loss of significant production capacity. Machine operators frequently choose to continue operating the machine, if only one process chamber has malfunctioned and is not usable. This choice is made even though the operation of the processing machine without the use of one of its process chambers results in higher operating costs and lower efficiencies. The reason for this choice is that over a relatively short period of time, a processing machine that has been left on-line, with perhaps only eleven of its twelve process chambers working, can produce more finished product than a processing machine that must be temporarily taken off-line to replace or repair a single malfunctioning process chamber.
An operator who has decided to continue operating a processing machine with an inoperable process chamber must ultimately repair that chamber, and take the entire machine off-line. Typically, the entire machine is taken off-line when a second or third chamber needs to be serviced, or when some other event in the fab provides an opportunity to service the machine without further interrupting production.
Manufacturing of microelectronic devices involves using various kinds of chemicals. These chemicals are frequently in the liquid state, but on occasion may be in gas or vapor state. These chemicals are highly pure, and thus expensive. Some of the chemicals used in these processes, such as hydrogen fluoride and other strong acids and oxidizers, are also toxic. As a result, the use, retention, and disposal of these chemicals require sophisticated equipment and extensive precautions, and can as a result be expensive. Consequently, it is desirable to lower the amount of these chemicals used in the manufacture of microelectronic devices. To prevent the release of toxic emissions, it is also necessary to retain those chemicals and their vapors within the machines, and to provide means for properly disposing of those vapors without releasing them to the ambient air.
It will be understood from the above that to ensure maximum production, it is highly desirable to create process chambers that have a high degree of reliability. One way of increasing that reliability is to create process chambers having a mechanically simpler construction.
It is also desirable to design process chambers that help to keep the chemicals used in processing within the process chamber, so as to lower the costs of purchasing and disposing of those chemicals, and so as to permit the proper disposal of any amounts of those chemicals that will not be reused.
Finally, it is highly desirable to create process chambers that more effectively direct drying air over the wafers used to make microelectronic devices, and to keep clean the end effectors used to insert and remove wafers. Designs having these effects would further reduce the likelihood that tiny particles of dust, dirt, metals, and manufacturing chemicals will remain upon the surface of those wafers, and damage the microelectronic resulting devices.